freebsd-dev/lib/libkse/thread/thr_pspinlock.c
David Xu c095b4a999 Add code to support pthread spin lock.
Reviewed by: deischen
2003-09-09 06:57:51 +00:00

155 lines
3.5 KiB
C

/*-
* Copyright (c) 2003 David Xu <davidxu@freebsd.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $FreeBSD$
*/
#include <errno.h>
#include <stdlib.h>
#include <pthread.h>
#include <atomic_ops.h>
#include "thr_private.h"
#define SPIN_COUNT 10000
int
pthread_spin_init(pthread_spinlock_t *lock, int pshared)
{
struct pthread_spinlock *lck;
int ret;
if (lock == NULL || pshared != PTHREAD_PROCESS_PRIVATE)
ret = EINVAL;
else if ((lck = malloc(sizeof(struct pthread_spinlock))) == NULL)
ret = ENOMEM;
else {
lck->s_lock = 0;
lck->s_owner= NULL;
*lock = lck;
ret = 0;
}
return (ret);
}
int
pthread_spin_destroy(pthread_spinlock_t *lock)
{
int ret;
if (lock == NULL || *lock == NULL)
ret = EINVAL;
else if ((*lock)->s_owner != NULL)
ret = EBUSY;
else {
free(*lock);
*lock = NULL;
ret = 0;
}
return (ret);
}
int
pthread_spin_trylock(pthread_spinlock_t *lock)
{
struct pthread_spinlock *lck;
struct pthread *self = _pthread_self();
int oldval, ret;
if (lock == NULL || (lck = *lock) == NULL)
ret = EINVAL;
else if (lck->s_owner == self)
ret = EDEADLK;
else if (lck->s_lock != 0)
ret = EBUSY;
else {
atomic_swap_int((int *)&(lck)->s_lock, 1, &oldval);
if (oldval)
ret = EBUSY;
else {
lck->s_owner = _pthread_self();
ret = 0;
}
}
return (ret);
}
int
pthread_spin_lock(pthread_spinlock_t *lock)
{
struct pthread_spinlock *lck;
struct pthread *self = _pthread_self();
int count, oldval, ret;
if (lock == NULL || (lck = *lock) == NULL)
ret = EINVAL;
else if (lck->s_owner == self)
ret = EDEADLK;
else {
do {
count = SPIN_COUNT;
while (lck->s_lock) {
#ifdef __i386__
/* tell cpu we are spinning */
__asm __volatile("pause");
#endif
if (--count <= 0) {
count = SPIN_COUNT;
_pthread_yield();
}
}
atomic_swap_int((int *)&(lck)->s_lock, 1, &oldval);
} while (oldval);
lck->s_owner = self;
ret = 0;
}
return (ret);
}
int
pthread_spin_unlock(pthread_spinlock_t *lock)
{
struct pthread_spinlock *lck;
int ret;
if (lock == NULL || (lck = *lock) == NULL)
ret = EINVAL;
else {
if (lck->s_owner != _pthread_self())
ret = EPERM;
else {
lck->s_owner = NULL;
atomic_swap_int((int *)&lck->s_lock, 0, &ret);
ret = 0;
}
}
return (ret);
}